Is Washington D.C. Radioactive?

Folks in Washington D.C. may be wondering why helicopters have been flying overhead for weeks now. According to cbslocal they have been conducting tests for radiation above portions of the Washington, D.C. area. The copters are equipped with gamma radiation sensing technology. Was there some sort of leak?No, this is occasionally done to detect naturally-occurring radiation increases. The National Nuclear Security Administration (NNSA) has been flying the radiation missions since Dec. 27, 2012 and they will continue until next Friday, the 11th. Should the need to inspect ever happen in Central New York, NNSA says they'll make the public aware of the upcoming flights so that citizens who see the low-flying aircraft are not alarmed. Here is the official statement from NNSA.